A new study published in the journal Nature Climate Change has revealed “significant progress” in reducing levels in the atmosphere of chemicals that destroy Earth’s protective ozone layer.

Decline of harmful hydrochlorofluorocarbons (HCFCs)

The findings show, for the first time, a notable decline in the atmospheric levels of potent “ozone-depleting substances” (ODS) called hydrochlorofluorocarbons (HCFCs). These are harmful greenhouse gases, so a reduction should also lessen global warming.

The Montreal Protocol introduced controls on the production and usage of ODS, which were once widely used in manufacturing hundreds of products, including refrigerators, aerosol sprays, foams and packaging. HCFCs were developed as replacements for chlorofluorocarbons (CFCs) and CFC production has been banned globally since 2010.

Replacement with non-ozone-depleting compounds

According to lead author Luke Western, Marie Curie Research Fellow at the University of Bristol’s School of Chemistry, “production of HCFCs is currently being phased out globally, with a completion date slated for 2040. These are being replaced by non-ozone-depleting hydrofluorocarbons (HFCs) and other compounds. By enforcing strict controls and promoting the adoption of ozone-friendly alternatives, the protocol has successfully curbed the release and levels of HCFCs into the atmosphere.”

The results rely on high-precision measurements at globally distributed atmospheric observatories, using data from the Advanced Global Atmospheric Gases Experiment (AGAGE) and the National Atmospheric and Oceanic Administration (NOAA).

Two forms of ozone

The good: In the atmosphere, good O₃ (ozone) protects us from the sun’s harmful UV rays. The famous hole in the ozone layer was created by the use of CFCs. These are now banned, so the hole is shrinking.

The bad: At ground level in urban environments, bad O₃ (in the form of photochemical smog) is created by the reaction of urban pollution and sunlight. It becomes a powerful urban pollutant with negative health effects, as noted in What’s Worse Than Global Warming?

Citation: Western, L. M., Daniel, J. S., Vollmer, M. K., Clingan, S., Crotwell, M., Fraser, P. J., Ganesan, A. L., Hall, B., Harth, C. M., Krummel, P. B., Mühle, J., Salameh, P. K., Stanley, K. M., Reimann, S., Vimont, I., Young, D., Rigby, M., Weiss, R. F., Prinn, R. G., . . . Montzka, S. A. (2024). A decrease in radiative forcing and equivalent effective chlorine from hydrochlorofluorocarbons. Nature Climate Change, 1-3. https://doi.org/10.1038/s41558-024-02038-7

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